Fujitsu MB90335 Series Hardware Manual page 249

CHAPTER 11 USB FUNCTION
11.4 Operation Explanation of USB Function
3. Temporarily disable the external interrupt. Change the interrupt setting to detect "L" level inputs to the
external interrupt pin, and then clear and re-enable the external interrupt.
4. Perform initialization (complete initialization including the USB Function Register). See "Example
Register Initialization and Operation Startup Procedure".
5. Clear the HCON bit in the UDCC register and connect the D+ pull-up resistor. (Clear the HCON bit
even if not performing control of the pull-up resistor.)
Note:
You do not need to allow for the above VBUS stabilization time in your program if using an external
noise filter on the external interrupt pin.
●
Detecting disconnection
VBUS
Disconnect from host
ENx
ERx
{LBx,LAx}
On recovery from stop mode
SUSP
USTP
HCON
The device uses the following sequence to detect a disconnection from the host PC.
1. Detection of an "L" level on the external interrupt pin connected to VBUS indicates disconnection from
the USB host.
2. On recovery from stop mode:
After waiting for the oscillation stabilization time, clear SUSP in the UDCS register followed by
USTP in the UDCC register.
When not recovering from stop mode:
Wait for the VBUS stabilization time.
3. Temporarily disable the external interrupt. Change the interrupt setting to detect "H" level inputs to the
external interrupt pin, and then clear and re-enable the external interrupt.
4. Set the HCON bit in the UDCC register and disconnect the D+ pull-up resistor. (Set the HCON bit even
if not performing control of the pull-up resistor.)
Note:
You do not need to allow for the above VBUS stabilization time in your program if using an external
noise filter on the external interrupt pin.
228
Figure 11.4-5 Operation When Detecting Disconnection
{0,0}
VBUS stabilization
time or oscillation
stabilization time
FUJITSU MICROELECTRONICS LIMITED
MB90335 Series
Change in source level
{0,1}
Set disconnection
CM44-10137-6E